chore: update dependabot and mergify (#2463)

update dependabot and mergify

Author: mpoke

Diff for: .github/dependabot.yml

@@ -87,3 +87,13 @@ updates:
     open-pull-requests-limit: 0
     labels:
       - dependencies
+
+  - package-ecosystem: gomod
+    directory: "/"
+    schedule:
+      interval: daily
+    target-branch: "release/v6.4.x"
+    # Only allow automated security-related dependency updates on release branches.
+    open-pull-requests-limit: 0
+    labels:
+      - dependencies

Diff for: .mergify.yml

@@ -65,4 +65,12 @@ pull_request_rules:
     actions:
       backport:
         branches:
-          - release/v6.3.x
+          - release/v6.3.x
+  - name: Backport patches to the release/v6.4.x branch
+    conditions:
+      - base=main
+      - label=A:backport/v6.4.x
+    actions:
+      backport:
+        branches:
+          - release/v6.4.x